Conservation and Management

Shooting And Trapping

Previously taken from North American colonies in large numbers by fishermen and used as bait for cod-fishing; some persecution by fishermen at Baccalieu I., Newfoundland, in 1940s, but today colonies protected as provincial reserves or as federal migratory bird sanctuaries (Bent 1922, Chapdelaine 1996, J. Chardine pers. comm.). At sea, gannets excited by fish are still killed by shooting, hooking, and by hand when they land on or near fishing boats; in some cases, they are not killed, but left to die by being released with their heads or legs tied to a wing, or their mandibles secured with a rubber band. For a complete account of past and present human harvest of gannets from different colonies, and their varied uses, see Nelson 1978a .

Pesticides And Other Contaminants/Toxins

Relatively little affected by oiling. As their foraging methods largely preclude seeing fish under oil slicks, gannets seldom dive into or swim far enough on or under water to become coated with oil. Hatch-year young vulnerable to oiling during their first month at sea, while unable to fly (Nelson 1978a).

Because of their trophic status, and preference for large fish, gannets especially prone to receive large quantities of certain toxic chemicals. Because large fish contain more organochlorine residues, both in absolute and relative terms, than small ones, and because gannets feed extensively on large fish, they tend to contain higher concentrations of organochlorines than other seabirds (Parslow and Jefferies 1977). Death toll due to toxins such as PCBs and DDE difficult to estimate, because they may contribute to death without being actual cause. At Bonaventure I., Québec, during late 1960s and early 1970s, low hatching success (<40%) and thus low overall productivity was attributed to reduced thickness of eggshells resulting from high concentrations of DDE, DDD, DDT, and Dieldrin in eggs (see Breeding: eggs, above; Nelson 1978a, Chapdelaine et al. 1987). Since ban on DDT and restricted use of PCBs in 1970s, levels of both contaminants have declined dramatically in gannet eggs; at Bonaventure I., Québec, lipid weight concentrations of DDE in eggs declined from 435.6 ppm ± 44.1 SD (n = 10) in 1968 to 29.2 ppm ± 2.6 SD (n = 6) in 1984; levels of DDD, DDT, Dieldrin, and PCBs showed similar patterns of decline during same period, while overall breeding success at the colony increased from <40% to >75% (Chapdelaine et al. 1987). Long-term trends in declining organochlorine contaminant levels in gannets and their eggs have also been observed in e. Atlantic colonies (Fimreite et al. 1980, Barrett et al. 1996).

High concentrations of mercury (Hg) and cadmium (Cd) have been reported in various studies (1968–1993) of Northern Gannets and their eggs (Parslow and Jefferies 1977, Fimreite et al. 1980, Barrett et al. 1996, Thompson et al. 1998); results suggest that factors other than just trophic status are important in determining exact levels. Along coast of Norway and in Barents Sea, where background levels of Hg in the water are very low, high levels of Hg in eggs attributed to consumption by gannets of wide-ranging fish, such as coalfish (Fimreite et al. 1980); in Britain, levels of Hg and Cd higher in gannets feeding in estuarine areas than those feeding in more open waters (Parslow and Jefferies 1977). As surface feeders, gannets tend to have lower levels of Hg than do seabirds that feed in mesopelagic waters where methyl mercury levels are highest (Thompson et al. 1998). Long-term levels of Hg in gannets appear to be slightly elevated, but relatively stable at concentrations below threshold causing death; background levels, however, need to be continuously monitored in areas where birds feed in waters contaminated by agriculture and industry.

Ingestion Of Plastics And Lead

No reports of plastic or lead ingestion; known to occasionally ingest lethal metal rubbish that glints like a fish (Nelson 1978a), and a documented account of starvation following ingestion of a large piece of Styrofoam from a lobster-pot buoy (Dickerman and Goelet 1987).

Plastics are widespread, persistent environmental contaminants; at Funk I. and Cape St. Mary’s, Newfoundland, 97% of nests sampled contained plastic objects, including fishing gear (rope, line, netting), package strapping, bags or sheets, and hard plastic (shotgun-shell casings and lobster-pot tags; Montevecchi 1991); in e. Atlantic, 50% of nests at Bass Rock, 75% at Bempton, and 49% at Grassholm contain similar plastic materials (Nelson 1978a); no deaths, however, attributable directly to ingestion of plastics.

Collisions With Stationary/Moving Structures Or Objects

Fledging chicks at some colonies suffer high mortality as a result of crash landings in boulders and scree between departure site and open water (e.g., Ailsa Craig, w. Scotland); adults occasionally killed or seriously injured at breeding colonies making bad landings during windy conditions, or when attacked and upended by Great Skuas (Catharacta skua; Wanless 1983). At colonies where high levels of DDT derivatives and/or PCBs detected in either eggs or birds (e.g., Bonaventure I., Ailsa Craig), minor imperfections in coordination may cause an increase in landing accidents. During feeding frenzies, gannets may plunge-dive into boat decks, fish holds, and even fish-curing sheds, and while diving for offal between boats at night in artificial light may shear off wings against wire hawsers (Nelson 1978a).

Erosion and rock slides sources of mortality at some gannetries; at Great Bird Rock, Magdalen Is., Québec, the fine-grained, poorly consolidated red sandstone cliffs are extremely porous; during spring thaw, they often fracture, causing rock falls that kill adult gannets and crush eggs (Kirkham 1981).

Fishing Nets

Often drown when diving into fishing nets as they are being raised; in areas where line fishing still used, may be caught on lines and hauled on deck dead. Synthetic fiber lines and nets becoming an increasingly common cause of death at gannetries of both adult and young birds; birds die when they get entangled in net materials and become tethered to nets without being able to break cord or pull it loose (Nelson 1978a, Montevecchi 1991).

Degradation Of Habitat

Unlikely at most sites. Natural forces such as erosion and rock slides have caused some habitat loss on breeding islands by reducing surface area for nest sites and, in some cases, killing birds outright (e.g., Great Bird Rock). Construction of lighthouse on Great Bird Rock greatly reduced area at that colony for nests, as well creating a permanent disturbance for nesting birds. In Gulf of St. Lawrence, runoff from industrial, commercial, agricultural, and residential areas of chemicals a continuous threat to quality of species’ foraging habitat, as is overfishing throughout North American range. Effects of global warming may yet pose greatest threat to Northern Gannet, and many other seabirds, through its potential to greatly alter major ocean currents, and thus availability of shoaling fish.

Disturbance At Breeding Sites; Direct Human/Research Impacts

Disturbance at most sites minimal. Disturbance of breeding birds by aircraft, fishing boats, tourists, and researchers reported at some sites (Nelson 1978a). Flushing of adults and banding of chicks can be disruptive, if not done properly. Tourists allowed to visit Bonaventure I. and Cape St. Mary’s under guidelines that minimize disturbance to nesting birds.

Conservation Status

Federally protected in Canada and U.S. as a migratory nongame bird. All North American populations currently increasing at >3.0%/yr, and thus not warranting any special conservation status.

Measures Proposed And Taken

Five of the 6 North American colonies are afforded federal or provincial protection (only Anticosti I. lacks this). Bonaventure I. protected as a Provincial Ecological Reserve; Bird Rocks a federal migratory bird sanctuary. As an ecological reserve, colony on Bonaventure I. accessible to general public for photography and viewing. All 3 Atlantic colonies—Funk I., Baccalieu I., and Cape St. Mary’s—are protected as Newfoundland Provincial Ecological Reserves. Under provincial protection, people cannot land on colonies without permits, except in case of Baccalieu I. where permits are available for activities outside of colony, such as berry picking, and on Cape St. Mary’s, where general public allowed to enter reserve to view colony (J. Chardine pers. comm.).

Effectiveness Of Measures

All protective measures taken since early 1900s have had a positive effect on colonies, as all currently growing at a sustained rate.